Imagine a huge salt flat like Bonneville or Salar de Uyuni. Due to other logistical concerns, commerce between the economic powers on either side of the flat is forced travel across it. This has resulted in the regular caravan crossing this flat slowly growing to the size of an city.
Typically, the city remains still on either end of the flat. When the rainy season arrives the flat floods with an inch or two of water and the predictable seasonal winds pick up. The city then raises its sails, and like the sailing stones of Racetrack Playa, it rides the wind to the other side.
How feasible is this setup? What city construction traits would be required? What natural conditions would encourage this?
A few notes on the situation:
The city is built atop numerous parallel skids that are the only places it touches the ground.
It's built of the lightweight materials like balsa wood and cloth. People pay handsomely for passage in the city and for every ounce of cargo they bring.
The salt flat environment is somewhat hostile to most animals. Beasts of burden, like horses or oxen, have a ~50% survival rate when attempting to cross without the city.
The city doesn't need to be a single cohesive unit, but I'd like it to have a single central mobile structure instead of being a collection of tents and the like.
Age of sail era technology is available, but still rare and expensive in this region.